Carrier assembly for movably supporting a fifth wheel assembly

ABSTRACT

A carrier assembly is mounted on the spaced frame members of a tractor for movably supporting a fifth wheel assembly thereon. An integral one piece slide rail is secured to each of the frame members and has a plurality of individual rack sections separately welded to a U-shaped member of the slide rail. Each of the rack sections contain a plurality of spaced teeth. The teeth extend into a channel formed in mounting brackets of a carriage assembly of the fifth wheel to slidably mount the carriage assembly on the carrier assembly. A leg of the U-shaped member extends into a channel formed in the carriage assembly and is engaged by a set bolt to adjust the carriage assembly for various frame widths. A pair of stop assemblies are adjustably movably mounted across the ends of the slide rails of the carrier assembly. A pair of adjustable plungers secure the carriage assembly in a fixed position on the carrier assembly.

BACKGROUND OF THE INVENTION

[0001] 1. Technical Field

[0002] The invention relates generally to fifth wheel assemblies forcoupling semi-trailers to tractors. More particularly, the inventionrelates to a carrier assembly which is mounted on the vehicle frame formovably supporting the fifth wheel supporting carriage. Even moreparticularly, the invention relates to such a carrier assembly which isadjustable for various width tractor frames and which facilitatespositioning and replacement of the carriage on the trailer.

[0003] 2. Background Information

[0004] Large highway freight trailers are usually coupled to a tractorby a fifth wheel assembly may include a top plate and a side bracket orcarriage assembly having a locking device which engages the slidebracket in a selected position. The fifth wheel top plate is mounted onthe carriage assembly which is movably adjustably mounted on a carrierassembly which is secured to the tractor frame.

[0005] These slide plates or carrier assemblies are usually custom madeto fit a particular type of tractor due to the size of the tractorframe. For certain applications it is necessary to adjust the positionof the carriage assembly on the carrier assembly in order for thelocking mechanism to be compatible with the location of the trailer kingpin to provide a desired weight distribution on the rear suspension ofthe tractor. Likewise, this position affects the turning radius that canbe achieved between the tractor and trailer. This adjustment of thecarrier and carriage assemblies with respect to each other and to thetractor frame is relatively complicated and expensive due to the weldingand unwelding of various parts.

[0006] Carrier assemblies have various stop plates welded across theends of the carrier to limit the position of the carriage assembly toprevent excessive movement of the carriage on the carrier assemblyresulting in a dangerous turning radius and undesirable weightdistribution on the tractor rear wheels. Heretofore, these stop memberswere welded into position and required breaking of the weld andrewelding the stop plate in a newly desired position, especially whenreplacing the slide plate assembly for maintenance or adaptability foruse with a different trailer.

[0007] Another problem with existing fifth wheel assemblies and inparticular the carrier assembly therefor, is that the racks along whichthe carriage assembly is movably mounted and subsequently positioned bya pair of opposed plungers or other retention mechanism, are usuallysingle linear lengths of a rack which require replacement of the entirerack should one of the teeth become damaged. This is an expensiveprocedure requiring numerous welds to be broken in order to remove therack and then rewelded along the entire length once the new rack is putin place. Likewise, the cost of the new rack is expensive for replacingonly one or several broken teeth.

[0008] Still another problem with existing carrier assemblies is theunequal weight distribution of the carriage and slide plate on thecarrier assembly resulting in increased maintenance problems.

[0009] Another problem with existing fifth wheel assemblies is that thespring biased plungers which secure a carriage assembly in a fixedposition on a carrier assembly, may require replacement in order tomatch a particular width trailer frame. This is expensive andundesirable. Furthermore, over time, the biasing force of the plungerbiasing springs will weaken due to wear, temperature and the harshenvironment in which they are located, which could cause prematurerelease of the plungers from the carrier rails.

[0010] Thus, the need exists for an improved carrier assembly formovably supporting a carriage assembly thereon of a tractor fifth wheelto eliminate problems with prior art carrier assemblies.

SUMMARY OF THE INVENTION

[0011] The present invention provides a carrier assembly for movablysupporting a fifth wheel assembly of a tractor trailer combination whichis readily adjustably mounted on the spaced frame members of a tractorby a plurality of bolts along the length of the frame mounting angle.

[0012] Another aspect of the invention provides a carrier assemblyhaving adjustable stop members at opposed ends of the carrier which canbe slidably adjusted easily along the length of the carrier in order toproperly position the carriage assembly thereon, and which can be easilyremoved to permit replacement of the carriage and the slide plateassemblies.

[0013] Still another feature of the invention is the forming of thecarrier assembly slide rails as integral one piece members having aU-shaped portion on which the rack is welded whereby each of the sliderails is easily mounted on the tractor frame member and is able toreceive and distribute the weight of the carrier in a more efficient andeffective manner.

[0014] A further aspect of the invention is forming the racks on theslide rails of a plurality of rack segments, each segment being securedto the slide rail by a pair of welds, whereby only a single segment needby replaced should one or more of the teeth be damaged avoiding theheretofore required replacement of the entire rack.

[0015] A feature of the improved carrier assembly is the adjustabilityof the mounting brackets for the stop members enabling them to bemounted on tractor frame members of various spacings replacing theheretofore single piece stop members that are welded on the space framemembers.

[0016] Another aspect of the invention is providing locking plungers forsecuring the carriage assembly in a fixed position on the carrierassembly which are adjustable in length to compensate for differentwidth trailer frames and to ensure a constant spring tensioning forcefor maintaining the plunger teeth in engagement with the teeth on thecarrier assembly rails to prevent premature release.

[0017] The foregoing advantages, construction and operation of thepresent invention will become more readily apparent from the followingdescription and accompanying drawings.

BRIEF DESCRIPTION OF THE DRAWINGS

[0018] The preferred embodiment of the invention, illustrative of thebest mode in which applicant contemplates applying the principles, isset forth in the following description and is shown in the drawings, andis particularly and distinctly pointed out and set forth in the appendedclaims.

[0019]FIG. 1 is a diagrammatic side elevational view of a tractortrailer combination connected together by a fifth wheel assembly;

[0020]FIG. 2 is an enlarged fragmentary side elevational view of thefifth wheel assembly movably mounted on a carriage which is adjustablymounted on the improved carrier of the invention which is attached tothe frame members of the tractor;

[0021]FIG. 3 is an enlarged top plan view of FIG. 2;

[0022]FIG. 4 is an enlarged fragmentary top plan view of the fifth wheelassembly with portions removed therefrom;

[0023]FIG. 4A is an enlarged fragmentary view of the encircled portionof FIG. 4;

[0024]FIG. 4B is an enlarged fragmentary sectional view taken on line4B-4B of FIG. 4A:

[0025]FIG. 5 is an enlarged fragmentary sectional view taken on line5-5, FIG. 4;

[0026]FIG. 6 is a top plan view of the carrier assembly mounted on thespaced frame members of a tractor;

[0027]FIG. 7 is an enlarged fragmentary view with portions broken awayand in section, of the encircled portion of FIG. 6;

[0028]FIG. 7A is a bottom plan view of the stop member mounting bracketof FIG. 7;

[0029]FIG. 8 is an enlarged fragmentary sectional view taken on line8-8, FIG. 7;

[0030]FIG. 9 is a top plan view similar to FIG. 6 showing one of thestop members of the carrier assembly in an adjusted position;

[0031]FIG. 10 is an enlarged fragmentary top plan view showing the twomounting brackets of the carrier assembly stop member mounted on thespaced frame members of a tractor;

[0032]FIG. 11 is an enlarged fragmentary sectional view taken on line11-11, FIG. 10;

[0033]FIG. 12 is a view similar to FIG. 10 showing the stop membermounting brackets in an adjusted position from that of FIG. 10;

[0034]FIG. 13 is an enlarged sectional view taken on line 13-13, FIG.12,

[0035]FIG. 14 is a fragmentary side elevational view of the carrierassembly mounted on one of the tractor frame members having a damagedrack segment;

[0036]FIG. 15 is a view similar to FIG. 14 showing removal of thedamaged rack segment; and

[0037]FIG. 16 is a view similar to FIGS. 14 and 15 showing placement ofa new rack segment on the carrier assembly.

[0038] Similar numerals refer to similar parts throughout the drawings.

DESCRIPTION OF THE PREFERRED EMBODIMENT

[0039]FIG. 1 is a diagrammatic side elevational view of a usual tractortrailer combination indicated generally at 1, consisting of a trailer 2and a tractor 3 connected together by a fifth wheel assembly 4.Referring to FIGS. 2 and 3, fifth wheel assembly 4 consists of a usualtop plate assembly 5 having a V-shaped slotted opening 6 for receiving aking pin (not shown) of trailer 2 within the locking opening 8 of alocking mechanism. The particularly construction of top plate 5 and themanner of operating locking mechanism 9 are well known in the art, andthus are not described in further detail. Top plate 5 is pivotallymounted at 10 on a pair of spaced pedestals 11 to permit pivotalmovement of the top plate. Pedestals 11 are mounted on a slide bracketor carriage assembly 13 (FIG. 4) which is adjustably movably mounted onthe improved slide plate or carrier assembly, indicated generally at 15.The construction of carriage assembly 13 is well known in the art and isonly partially shown in FIG. 4 and briefly described below.

[0040] Carriage assembly 13 has a plunger assembly indicated generallyat 17, which includes a plunger support plate 18 and a pair of movableplungers 19 connected together by an adjustable link assembly 20. Eachplunger 19 includes a plurality of teeth 22 which are formed on aplunger plate 23 which is mounted on the outer end of an adjustmentscrew 26 (FIG. 4B) which is pivotally connected to a pair of links 31which are pivotally connected by a pin 21 (FIG. 4) at the center ofplunger assembly 17. The opposite ends of each link 31 are pivotallyconnected to adjustment screws 26 by pins 32. Teeth 22 are engageablewith teeth 24 of a pair of spaced racks 25 to secure carriage assembly13 in an adjusted position on carrier assembly 15.

[0041] In accordance with one of the features of the invention,adjustment screw 26 includes a threaded end 33 which is threadablyreceived within a threaded opening 34 formed in plunger plate 23 (FIG.4B). This enables the length of plunger assembly 17 to be adjusted forvarious width trailer frames and also enables plate 23 to be adjustedwith respect to spaced racks 25 as shown by arrow A, FIG. 4B, to changethe tension in compression coil springs 39 which bias plates 23 andcorresponding teeth 22 toward engagement with the teeth of rack 25. Theinboard end of each plate 23 is slidably located within an opening 44Aof a mounting plate 44 which is welded to plunger support plate 18.

[0042] Carriage assembly 13 includes a pair of stepped plates 28 onwhich pedestals 11 are mounted and further includes a cross plate 29extending between plates 28 for stabilizing carriage assembly 13together with plunger support plate 18. A link 30 extends diagonallybetween cross plate 29 and plunger support plate 18 to stabilizecarriage assembly 13. Carriage assembly 13 includes a pair of mountingbrackets 55 extending across the underside of stepped plate 28 formovably mounting carriage assembly 13 on carrier assembly 15 (FIG. 5).Only one bracket 55 is shown in FIG. 4 and is described further below.

[0043] Improved carrier assembly 15 is shown particularly in FIG. 6. Inaccordance with one of the features of the invention it includes a pairof adjustable end stop members 35, each of which includes a stop plate36 and a pair of end mounting brackets 37. Carrier assembly 15 furtherincludes a pair of improved slide rails indicated generally at 40, whichare mounted on spaced tractor frame members 27 for movably supportingcarriage assembly 13 on rails 40 as shown in FIG. 5. Tractor framemembers 27 are usually inverted U-shaped or L-shaped beams as shown inFIG. 5 having a vertically extending leg 27A and a horizontal top leg orwall 27B. Slide rails 40 are preferably substantially similar to eachother, and thus only one is described in detail and shown in thedrawings.

[0044] In accordance with another feature of the invention, slide rail40 (FIGS. 2, 5 and 6) is formed as an integral one piece member of rigidmetal and includes a flat vertically extending mounting leg 41containing a plurality of mounting holes 42 for receiving mounting bolts43 therethrough for rigidly attaching slide rail 40 to tractor frame leg27A. Slide rail 40 further includes a U-shaped member 45 formed by apair of spaced legs 46 and 47 joined by a base 48 which form a U-shapedchannel 49 therein. Leg 46 extends from mounting leg 41 and forms asubstantial 90° angle therebetween and extends along end and rests upontop surface 38 of tractor frame leg 27B.

[0045] In accordance with another feature of the invention rack 25 isformed by a plurality of rack segments 50 which are mounted on base 48of U-shaped member 45 by a plurality of welded connections 52.Preferably, there are at least two welded connections 52 for each racksegment 50, each connection having upper and lower welds 53. Each racksegment 50 includes a plurality of the individual teeth 24 which extendinboard from U-shaped member 45. In the preferred embodiment racksegments 50 have a linear length of approximately six inches.

[0046] Referring particularly to FIGS. 4 and 5, carriage assembly 13 isadjustably movably mounted on carrier assembly 15 by mounting brackets55 which extend generally throughout the length of pedestal supportplate 28 and are secured thereto by pairs of bolts 58. Bolts 58 alsoextend through and connect link 31 to an outwardly projecting tab 61, aplurality of which extend outwardly from the corners of plunger supportplate 18. Bolts 58 also connect tabs 56 to clamp 55, and to a generallyU-shaped bracket 57 through which plunger teeth segments 23 extend forengagement with racks 25.

[0047] Each mounting bracket 55 (FIG. 5) further includes a U-shapedchannel 64 formed by a lower leg 62 and stepped pedestal plate 28. Plate28 terminates in an outboard U-shaped channel forming member 67 having alower leg 68 which forms U-shaped channel 69 with stepped plate 28. Thecross sectional configuration of brackets 55 will remain similar to thatshown in FIG. 5 except for a short section (not shown) opposite ofplunger segments 23 whereon the vertical wall 54 extending betweenbracket 57 and pedestal plate 28 is cut away to permit the passage ofplunger teeth segment 23 therethrough.

[0048] As shown particularly in FIG. 5, mounting bracket 55 is securedin a selected fixed position on slide rail 40 by a threaded set bolt 72which is adjustably engaged in a thread hole 74 formed in member 67. Theinner end of bolt 72 engages the outer end of leg 47 of slide rail 40,and is secured in the fixed clamping engagement therewith by a lock nut73. Leg 47 of U-shaped member 45 of rail 40 is received in U-shapedchannel 69 with teeth 24 of rack segments 50 extending into U-shapedchannel 64.

[0049] As can be seen in FIG. 5, slide rail 40 provides various areas onwhich the weight of carriage assembly 13 is supported, such as the uppersurfaces of leg 47 and of teeth 24, leg 27B engaging leg 62, and leg 46supporting bracket leg 68 on top wall 27B of tractor frame 27. Thesevarious areas of support are provided by slide rail 40 for evenlydistributing and supporting the weight of carriage assembly 13 throughmounting brackets 55.

[0050] In accordance with a further feature of the invention, stopmembers 35 are adjustable in length to accommodate different widthtractor frame members as shown particularly in FIGS. 10-12 as well asbeing movably adjustable along the longitudinal length of carrierassembly 15 as shown particularly in FIG. 9. This width adjustment isobtained by the unique construction of mounting brackets 37. Referringparticularly to FIGS. 6-12, each mounting bracket 37 includes a mountingplate indicated generally at 80, having an in-turned end 81 which formsa U-shaped channel 82 for slidably receiving the outer end of leg 48 ofU-shaped member 45 therein for slidably adjustably mounting mountingbracket 37 on slide rail 40 (FIGS. 8 and 11). Mounting plate 80 includesa recessed area 83 formed between a pair of teeth 85 into which a tooth24 extends for engagement with adjacent teeth 85 which engages spacedteeth 24 formed on rack 25 as shown particularly in FIGS. 7 and 7A.Mounting plate 80 includes two pairs of holes 86 and 87 with holes 87extending through teeth 85 for receiving bolts 88 and 89 respectivelytherethrough, which are threadably engaged in aligned holes 90 and 91formed in a bottom clamping plate 93 (FIGS. 8 and 11). Mounting bracket37 is secured in a selected position along rack 25 by receiving one ofthe rack teeth 24 in area 83 formed between the pair of teeth 85 formedon the bottom surface of mounting plate 80.

[0051] Stop plate 36 is formed with a pair of opposed ends 95 and 96(FIGS. 10 and 11), each of which is formed with a pair slotted openings97 through which bolts 88 extend for securing plate 80 in an adjustedposition on the ends of stop plate 36. As shown in FIG. 10, stop member35 is in its shortest position or narrowest width as indicted by bracketX, due to the location of bolts 88 within slotted openings 97. FIG. 12shows stop member 35 in its longest position or greatest width asindicated by bracket Y, due to the location of stop bolts 89 withinslotted openings 97 of stop plate 36.

[0052] Thus, carrier assembly 15 is adaptable for use with tractorframes having various spacings without requiring substantialmodifications thereto by use of bolts 88 and slots 97. This eliminatesany welding as required in prior art carrier assemblies. Carrierassembly 15 is adaptable for various tractors having a range of framespacings which heretofore required separate specially designed carriersfor each particular tractor due to this difference in spacing requiringthe welding and permanent fixing of cross members thereon. Likewise,bolts 88 and 89 enable stop members 35 to be easily adjusted across thewidth of the slide rails 40 and longitudinally along tractor framemembers 27 to enable carrier assembly 15 to be adaptable to varioustractors and also to accommodate trailers having various king pinlocations in order to achieve various weight distributions on thetractor rear wheels, as well as effecting the turning radius of thetractor with respect to the trailer. Heretofore, these adjustments weremade permanently by welding fixtures to the carrier assembly and did notpermit ease of adjustment in the location of end stop members as in thepresent invention which is accomplished by a plurality of bolts whichare readily loosened and then tightened once the desired adjustmentshave been accomplished.

[0053] Likewise, plunger assembly 17 is easily adjusted as describedabove, enabling it to accommodate tractor frame members having variousspacings therebetween without requiring substantial modifications to theplunger assembly which is achieved easily by the threaded adjustment ofadjustment screw 26 in threaded opening 34 of plunger plate 23.

[0054] In accordance with still another feature of the invention asshown in FIGS. 14-16, rack 25 is formed by a plurality of rack segments50 each of which includes a plurality of the individual teeth 24. Thesegments are placed in an abutting relationship along slide rail 40 asshown by joint 100. Each segment 50 is secured by a welded connection52, with each welded connection consisting of top and bottom welds 53 asshown particularly in FIGS. 5, 8, 11, and 13. In the preferredembodiment, each rack segment 50 will have a length L (FIG. 16) ofapproximately six inches.

[0055] This feature enables a damaged tooth or several teeth as shown byrack segment 50A in FIG. 15, to be easily replaced by an undamaged racksegment 50B requiring only two welded connections 52 to be replaced andreapplied. This eliminates the heretofore replacement of the entire rack25, which in prior carrier constructions was a single longitudinallyextending rack formed as a single piece extending throughout the lengthof the carrier assembly. Thus, replacement of only one short racksegment is considerably cheaper and easier to accomplish then replacingthe entire rack as required in prior carrier assemblies.

[0056] Accordingly, the improved carrier assembly for a fifth wheelassembly is simplified, provides an effective, safe, inexpensive, andefficient device which achieves all the enumerated objectives, providesfor eliminating difficulties encountered with prior devices, and solvesproblems and obtains new results in the art.

[0057] In the foregoing description, certain terms have been used forbrevity, clearness, and understanding; but no unnecessary limitationsare to be implied therefrom beyond the requirement of the prior art,because such terms are used for descriptive purposes and are intended tobe broadly construed.

[0058] Moreover, the description and illustration of the invention is byway of example, and the scope of the invention is not limited to theexact details shown or described.

[0059] Having now described the features, discoveries, and principles ofthe invention, the manner in which the improved carrier assembly isconstructed and used, the characteristics of the construction, and theadvantageous new and useful results obtained; the new and usefulstructures, devices, elements, arrangements, parts, and combinations areset forth in the appended claims.

What is claimed:
 1. A carrier assembly for movably supporting a fifthwheel assembly on a pair of spaced frame members of a tractorcomprising: a pair of slide rails adapted to be mounted on the spacedframe members, each of said slide rails being a integral one-piecemember having an attachment leg and a generally U-shaped memberextending inboard from the attachment leg; a rack containing a pluralityof teeth attached to each of the U-shaped rails and extending inboardtherefrom; at least one stop plate assembly extending between the pairof slide rails; and mounting brackets for securing the said one stopplate assembly in a selected position on said slide rails.
 2. Thecarrier assembly defined in claim 1 wherein the rack is attached to theU-shaped member by a plurality of welded connections.
 3. The carrierassembly defined in claim 2 wherein the rack consists of a plurality ofsegments, each segment containing a plurality of teeth; and in whicheach of said segments is attached to the U-shaped member by at least apair of welded connections.
 4. The carrier assembly defined in claim 3wherein each rack segment has a linear length of approximately 6 inches.5. The carrier assembly defined in claim 2 wherein each of the U-shapedmembers has a pair of spaced legs extending outwardly from a base; andin which the rack is attached to the base of said U-shaped member by thewelded connections.
 6. The carrier assembly defined in claim 1 whereinthe stop plate assembly includes a stop plate extending between themounting brackets; in which each of the mounting brackets include amounting plate which is secured to opposite ends of the stop plate; andin which at least one of the mounting plates is adjustably mounted onthe stop plate.
 7. The carrier assembly of claim 6 in which one of saidmounting plate and stop plate is formed with elongated openings forvarying the width of the stop plate assembly.
 8. The carrier assemblydefined in claim 7 in which the said one mounting bracket furtherincludes a clamp plate and a plurality of fasteners for securing one ofthe stop plate ends between the clamp plate and mounting bracket.
 9. Thecarrier assembly of claim 6 in which at least one of the mountingbrackets is formed with a curved end which slidably engages an outeredge of the U-shaped member of the slide rail; and in which at least onetooth is formed on said one mounting bracket and engage selected teethof the rack.
 10. A frame rail for mounting on a frame member of avehicle for movably supporting a fifth wheel assembly thereon, saidframe rail comprising: an integral one piece member having an attachmentleg for securing the frame rail to the frame member and a U-shapedmember extending from said attachment leg, said U-shaped member having apair of spaced legs extending from an intervening base and forming aslide channel therebetween; and a rack containing a plurality of teethattached to the base of said U-shaped member and extending therefrom.11. The frame rail defined in claim 10 wherein the attachment leg isformed with a plurality of holes for receiving fasteners therethroughfor attaching said leg to the frame member.
 12. The frame rail definedin claim 10 wherein the rack is attached to the U-shaped member by aplurality of welded connections.
 13. The frame rail defined in claim 10wherein one of the spaced legs of the U-shaped member is longer than theother of said legs; and in which said longer leg is adapted to besupported on the vehicle frame member.
 14. The frame rail defined inclaim 10 wherein the slide channel of the U-shaped member issubstantially U-shaped in cross section.
 15. In combination a pair ofspaced frame members on the rear of a tractor and a carrier assembly formovably supporting a fifth wheel assembly on said frame memberscomprising: a pair of slide rails adapted to be mounted on the spacedframe member, each of said slide rails being a integral one-piece memberhaving an attachment leg and a generally U-shaped member extending fromsaid attachment leg; a rack containing a plurality of teeth attached toeach of the U-shaped members and extending inboard therefrom; at leastone stop plate assembly extending between the pair of slide rails, saidstop plate assembly including a stop plate and a pair of end mountingbrackets; and fasteners for securing the stop plate to the mountingbrackets.
 16. The combination defined in claim 15 wherein the rack isattached to the U-shaped rail by a plurality of welded connections. 17.The combination defined in claim 16 wherein the rack consists of aplurality of segments, each segment containing a plurality of teeth andbeing attached to the rail by the welded connections.
 18. Thecombination defined in claim 16 wherein each of the U-shaped members hasa pair of spaced legs extending outwardly from a base; and in which therack is attached to the base of said U-shaped member by the weldedconnections.
 19. The combination defined in claim 15 wherein the stopplate assembly mounting brackets are adjustably secured to opposite endsof the stop plate; in which said mounting brackets are formed withcurved ends; and in which the said curved ends are slidably received inthe U-shaped members of the slide rails.
 20. The combination defined inclaim 15 in which each of the frame members has a side wall and a topwall; in which the attachment leg of the slide rail extends along and issecured to the side wall of the frame member; and in which the U-shapedmember rests upon the top wall of said frame member.
 21. The combinationdefined in claim 20 in which the attachment leg and frame member sidewall are formed with a plurality of spaced holes; and in which fastenersextend through certain of said holes for securing the slide rail on theframe member.
 22. The combination defined in claim 19 in which slottedopenings are formed in one of the stop plate and mounting brackets, andholes are formed in the other of said stop plate and mounting brackets;and in which fasteners extend through certain of said slotted openingsand holes to adjustably mount the stop plate on the mounting brackets.23. The combination defined in claim 15 in which a carriage assembly ismovably mounted on the slide rails by spaced mounting brackets; in whichsaid mounting brackets each include a first channel for slidablyreceiving the teeth of the rack therein; and in which a second channelis formed in each of the mounting brackets for receiving an end of theU-shaped member therein.
 24. The combination defined in claim 23 inwhich clamping bolts engage the end of the U-shaped member to secure themounting bracket on the slide rail.
 25. An adjustable stop member formounting on a pair of spaced slide rails of a carrier assembly whichmovably supports a fifth wheel assembly thereon, said stop membercomprising: A plate having a pair of opposed ends, said plate adapted toextend substantially between the slide rails of the carrier assembly;and a bracket mounted on each of the plate ends for mounting the plateon the slide rails, at least one of said brackets having an adjustingmechanism for adjusting the length of the stop member.
 26. The stopmember defined in claim 25 in which each of the brackets is formed witha pair of teeth and a plurality of mounting holes.
 27. The stop memberdefined in claim 26 including a clamp plate for securing each of thebrackets on the slide rails.
 28. The stop member defined in claim 25 inwhich one of the plate ends and brackets is formed with slotted openingsand the other of said ends and brackets is formed with holes; and inwhich fasteners extend through said slotted openings and holes toprovide the adjusting mechanism.
 29. A plunger assembly for securing acarriage assembly of a fifth wheel in a fixed position on a carrierassembly mounted on a trailer frame, said plunger assembly comprising: apair of spaced plunger plates each having at least one tooth forengaging the carrier assembly; a linkage extending between the pair ofplunger plates; and an adjusting mechanism for varying the spacingbetween the plunger plates.
 30. The plunger assembly defined in claim 29wherein the adjusting mechanism includes a threaded connection betweenthe linkage and the plunger plates.
 31. The plunger assembly defined inclaim 30 including a spring which biases the said one tooth towardengagement with the carrier assembly.